word = "学生姓名叫李小明，班级是21商务软件"
new_word = word.replace("21","20")
print(new_word)

word2 = "燕子去了，有再来的时候；杨柳枯了，有再青的时候；桃花谢了，有再开的时候。"
print(word2)
word3 = word2.replace("杨柳","荷花")
word4 = word3.replace("桃花", "木棉花")
print(word4)
